kramdownable.rb

module Kramdownable
  extend ActiveSupport::Concern
  include ActionView::Helpers::TextHelper

  def autolink_filter(content)
    auto_link(content, html: {target: '_blank'}, sanitize: false)
  end

  def kramdown
    Kramdown::Document.new(body || '', kramdown_options)
  end

  def kramdown_options
    {
      auto_id_prefix: 'toc-',
      auto_ids: true,
      input: 'GFM',
      coderay_line_numbers: nil
    }
  end

  def headers
    kramdown.root.children.select { |el| el.type == :header }
  end

  # h2だけ右下のtocとして出力する
  def headers_for_toc
    (0...headers.size).map do |number|
      toc_id = "#{kramdown_options[:auto_id_prefix]}section"
      toc_id += "-#{number}" if number > 0
      if headers[number].options[:level] == 2
        { toc_id: toc_id, value: headers[number].options[:raw_text] }
      else
        nil
      end
    end.compact
  end

  def to_html
    autolink_filter(kramdown.to_html)
  end
end